Proceedings of the 9th international conference on Energy Efficiency in Domestic Appliances and

429 Pages·2017·25.12 MB·English

Proceedings of the 9th
international conference on
Energy Efficiency in Domestic
Appliances and Lighting
(EEDAL '17)
Part III
Bertoldi, Paolo
2017
EUR 28961 EN
This publication is a report by the Joint Research Centre (JRC), the European Commission’s science and
knowledge service. It aims to provide evidence-based scientific support to the European policymaking process.
The scientific output expressed does not imply a policy position of the European Commission. Neither the
European Commission nor any person acting on behalf of the Commission is responsible for the use that might
be made of this publication.
Contact information
Name: Bertoldi Paolo
Address: European Commission, Joint Research Centre, Via Enrico Fermi 2749 - 21027 Ispra (VA), Italy
Email: [email protected]
Tel.: [phone]
JRC Science Hub
https://ec.europa.eu/jrc
JRC109209
EUR 28961 EN
PDF ISBN 978-92-79-77174-3 ISSN 1831-9424 doi:10.2760/113534
Print ISBN 978-92-79-77173-6 ISSN 1018-5593 doi:10.2760/68449
Luxembourg: Publications Office of the European Union, 2017
© European Union, 2017
Reuse is authorised provided the source is acknowledged. The reuse policy of European Commission documents
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How to cite this report: P. Bertoldi, Proceedings of the 9th International Conference on Energy Efficiency in
Domestic Appliances and Lighting (EEDAL '17) - Part III, EUR 28961 EN, Publications Office of the European
Union, Luxembourg, 2017, ISBN 978-92-79-77174-3, doi:10.2760/113534, JRC109209.
All images © European Union 2017
Contents
13 HEATING, COOLING AND WATER HEATING ....................................................... 889
Measured Performance of a High-Efficiency Solar-Assisted Heat Pump Water Heater .............. 890
Intelligent control of domestic and commercial point of use water heating and cooling applications 900
Green on-site power generation: Environmental considerations on small-scale biomass gasifier fuel-
cell CHP systems for the residential sector ................................................................... 909
US HPWH Market Transformation: Where We’ve Been and Where to Go Next ....................... 922
Demand-Response Performance of Electric Resistance and CO Refrigerant Heat Pump Water Heater
2
942
Advanced MOF-Water Adsorption Heat Pumps for Space Cooling and Heating ...................... 956
14 SMART APPLIANCES ....................................................................................... 969
Smart appliances and smart homes: recent progresses in the EU ....................................... 970
Thermostats in Residential Buildings: How Updated are They? What’s the “Smart” Penetration,
Turnover Rates, and the Remaining Savings Potential? ................................................... 985
A Luke-Warm Reception: Why Consumers Aren’t Hot for Smart Thermostats ......................... 999
The Radio Teleswitch: An historical perspective on the roll-out of domestic load control ........... 1014
Interaction between Home Energy Management and Smart Appliances .............................. 1023
ENERGY STAR: Energy Efficiency and the Smart Grid .................................................. 1040
Energy Reporting: Technology, Development, and Applications........................................ 1050
15 TEST METHODS ........................................................................................... 1064
Evaluation of performance tests of range hoods used for the European energy efficiency label .. 1065
A methodology to assess consumer relevant aspects for product testing ............................. 1073
New Efficiency Metric for Fans Enables New Approaches for Efficiency Regulations and Incentives
1082
Why is knowledge on measurement uncertainty so important in setting policies on energy efficiency?
1094
Telling the Truth - Validity of energy efficiency values of heat pumps determined under
laboratory conditions ....................................................................................... 1104
Following the evidence – How quality of appliance components can hint at non-compliance with
efficiency requirements ........................................................................................ 1113
Laboratory and Field Tests of an Efficient Fan Controller® in Cooling and Heating Mode on Residential
HVAC Systems .................................................................................................. 1118
Durability testing procedure for washing machines – approach and first learnings ................. 1133
16 LIGHTING ................................................................................................... 1146
Sustainable residential lighting practices and light pollution ............................................. 1147
Some Insights to the Lighting Electricity Consumption of Turkish Households ....................... 1161
A Language for Light: A User Interface Standard for Lighting Control ................................. 1171
Reducing carbon dioxide emissions by global transition to LED lighting in residential buildings .. 1183
Relative drift towards blue spectral region of white LEDs during ageing .............................. 1192
LED Lighting Efficiency: a systems approach .............................................................. 1203
i
17 DEMAND RESPONSE .................................................................................... 1213
Recent Developments in Access to Consumer Consumption and Billing Data for Use in Distributed
Energy Resource (DER) Programs .......................................................................... 1214
Addressing the gap between individual and system wide demand response programs ............ 1232
Evaluation of the performance of Aggregated Demand Response by the use of Load and
Communication Technologies Models....................................................................... 1254
Do low-income electricity subsidies change peak consumption behavior? ............................ 1270
18 SMART METERS AND FEEDBACK SYSTEMS ...................................................... 1281
Utilizing Flexibility of Hybrid Appliances in Local Multi-modal Energy Management ................. 1282
A new approach for residential real-time energy feedback using a low-cost non-intrusive load
monitoring framework .......................................................................................... 1298
Residential Consumer Driven Energy Management and Feedback .................................... 1311
ii
13 HEATING, COOLING AND WATER HEATING

889
Measured Performance of a High-Efficiency Solar-Assisted Heat
Pump Water Heater
Carlos Colon, Danny Parker Tim Merrigan, Jeff Maguire
Florida Solar Energy Center National Renewable Energy Laboratory

Abstract
This paper describes a novel solar photovoltaic-assisted heat pump water heater (PV-HPWH). The
system uses two 310 W PV modules, micro-inverters and innovative controls to produce and store
p
daily hot water. The system likely costs half that of solar thermal systems, with greater reliability, no
freeze protection and potentially superior performance in cloudy locations. Moreover, no net metering
is needed for the PV, which with two modules makes for a simple installation.
The HPWH controls have been modified through experimentation such that higher tank temperatures
are achieved during the day when solar availability is high while avoiding triggering the compressor
during early morning hot water draws. When tank temperatures are satisfied, the remaining PV
electricity is stored in the tank using staged electric resistance elements. Typical performance sees
hot water storage greater than 65⁰C at sunset. A mixing valve provides hot water at the target
temperature (52⁰C). By altering tank temperature, an equivalent of ~2 kWh of electrical energy is
stored for use during evening hours. Typically, there is no grid electricity demand during the utility
summer peak demand window.
The system has been tested for twelve months in a laboratory at the Florida Solar Energy Center.
Realistic hot water draws were imposed with detailed data recorded on system performance. Long
term COP, averaging 5.4, has been as high as 8.0 during sunny summer days. Average daily grid
electricity consumption has been 1.2 kWh/day– less than many refrigerators. Prospects for further
development and refinement are discussed.
Introduction
Reducing energy use for heating water remains a major challenge around the world. Field data shows
that heat pump heat pump water heaters (HPWH) can significantly reduce electricity needs in warm
climates. For instance, in eight Central Florida homes in 2013, comparison of one year pre and post-
retrofit hot water energy after changing from electric resistance to HPWH showed 68% (5.3 kWh/day)
sub-metered savings [1]. Effective COPs for 2012-generation HPWHs are approximately 1.5 – 2.5,
depending on climate, location within a building, and machine characteristics [2]. Recent work has
shown that HPWH interaction with space conditioning loads are potentially significant with interior
locations—for instance, reducing cooling loads by more than 5% in warm climates [3].
For electric water heating to be an attractive substitute against efficient natural gas heating for
reducing greenhouse gas emissions, seasonal system electrical COP must be greater than 3.0 at
average emission rates for U.S. generation resources.1 While solar thermal water heating systems
have high COPs (often above 3.5), these systems are typically expensive and can have high
maintenance needs [10]. At the November 2013 ACEEE Hot Water Forum in Atlanta, a thought-
provoking presentation compared solar thermal water heating systems with heat pump water heaters
(HPWH) powered by photovoltaic (PV) modules. [4] The simple premise was that with the introduction
of high-efficiency HPWHs in the U.S. market coupled with rapidly falling PV prices, it was now more
cost-effective to install a PV-driven HPWH rather than a conventional solar thermal system. Using an
example of a 1.0 to 1.3 kW PV system powering a HPWH with an Energy Factor (EF) of 2.5, it was
calculated that a PV-driven HPWH currently had a $5,000 to $8,500 installed cost before incentives,
while the installation of a conventional solar water heating system cost $7,000 to $10,000 before
incentives. In addition, the PV-driven HPWH saved more energy, was easier to install with no
plumbing, used less space, required less maintenance, and could not leak, overheat, or freeze.

1 This calculation assumes an emission rate of 681 g/kWh for average U.S. electrical generation against an emission rate of
227 g/kWh for natural gas at an energy factor of 0.80 for an efficient new natural gas hot water systems (condensing or
tankless). https://www.epa.gov/energy/greenhouse-gases-equivalencies-calculator-calculations-and-references
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Background
Water heating in residential and small commercial buildings continues to pose a challenge as the
overall efficiency of buildings improves with minimum energy efficiency code requirements for air
conditioning, lighting and building envelope occurred over the last decade. Although some
improvement in the minimum energy efficiency for storage water heaters in the United States was
implemented in 2015, energy efficiency improvements to other building components appear to provide
significant potential energy savings compared to those applied to standard water heating appliances.
Over the last 10 years, PV has gained momentum in the U.S. with improvement in conversion
efficiencies as well as decreased cost. The use of PV to heat potable water has been discussed by
many researchers. Previously in 1998-99, direct resistance water heating using PV was first explored
and tested at the Florida Solar Energy Center (FSEC) in a novel design by Dougherty and Fanney [6].
The system featured a 1060 W PV array with proprietary control algorithm to switch between a three-
p
resistance capable heating element to maximize power transfer. In recent years, other PV system
designs for dedicated water heating have evolved into the market.
While PV has been combined with heat pumps for solar-assisted space heating and air conditioning,
there are not many instances where PV is used with a heat pump for water heating. In one of the few
examples, Aguilar et al. [6] conducted an experimental year-long study of a PV-assisted split-system
heat pump for water heating in Spain. The system consisted of two PV modules of 235 Watts each, a
189 liter storage tank, and a heat pump with a long-term coefficient of performance (COP) of 3.15.
Under a typical residential hot water load, the annual solar contribution was greater than 60%.
Compared to standard electric resistance, residential heat pump water heaters provide considerable
energy savings due to their high efficiency. Currently in the United States, HPWH’s ranging from 189
to 303 liters are rated with an energy factor (EF) as high as 3.4 as indicated under the advanced
product list published by the Northwest Energy Efficiency Alliance (NEEA). [7] The design and
integration of PV and heat pump water heaters provide a synergistic combination to improve overall
efficiency at a reasonable cost.
As part of the effort towards zero energy buildings and high efficiency water heating systems, the
Florida Solar Energy Center (FSEC) -- working under contract with the National Renewable Energy
Laboratory (NREL) -- has been developing a PV-assisted heat pump water heater (PV-HPWH)
prototype (Figure 1). The system combines two 310 W solar photovoltaic (PV) modules and grid-tied
p
microinverters with a commercially available 189-liter HPWH. Using the HPWH’s integrated tank to
store solar energy, the PV is used without any grid interconnection, thus avoiding potential net
metering issues that have recently emerged in many U.S. states.
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Figure 1: PV modules (310 Watts each) and 189–Liter HPWH shown with added insulation
The PV-assisted HPWH prototype began evaluation in February 2016 at the FSEC hot water systems
laboratory in Cocoa, Florida. The testing utilized an automated hot water load schedule totaling 223
liters per day, typical of an average 3-4 person family. An average COP of 3.5 was obtained for the
first month of February. (By subtracting the PV-generated electricity produced from the total electricity
used by the system, the net grid electricity is used in the calculation of the PV-HPWH system COP.)
Further analysis excluding the PV contribution indicated a HPWH-alone performance COP of 2.1 in
February which is virtually identical to manufacturer claims for the unit [8]
The PV-HPWH prototype evolved with a series of automated control improvements through the spring
and summer. Beginning on March 2016, the system was upgraded to autonomously change the
thermostat setting from 52⁰C (baseline) to 60⁰C depending on the power produced by the PV and
micro-inverters. The thermostat setting change was triggered by a minimum PV power threshold of
260 W averaged over one minute. Following that change, during the month of April, the factory-
supplied 4500 Watt bottom heating element was removed and replaced with one of a lower wattage
(750 W). The bottom heating element was then re-wired and independently activated via a controller
board and software developed at FSEC.
System Description
A diagram of the PV-driven HPWH as tested at FSEC can be seen in Figure 2. The HPWH used in
the study is rated at 600 Watts: however, depending on tank temperatures, data indicated that power
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draw changes between 490 and 700 Watts. A higher than rated power draw was routinely
demonstrated as the compressor operated and heated water approaching the highest thermostat
setting of 60⁰C. Furthermore, fix-mount PV modules facing south at a 24o tilt produce the highest
power during mid-day hours (11:00 am – 2:00 pm). On average, the power produced by the PV
modules was 369 Watts during the mid-day period. The balance or net energy to operate the HPWH
compressor is sourced from the grid.

Figure 2: Schematic diagram of prototype PV-assisted HPWH.
To match the energy produced the PV modules to the electric resistance heating element load, power
control circuitry using capacitive reactance was implemented, resulting in a two-stage resistance
heating element (192 and 396 Watts). Further development of the FSEC-developed controller led to
techniques to maximize the compressor operation efficiency and store most PV energy as hot water.
Once a full tank of 60⁰C temperature water was reached and the compressor was shut-off by the
HPWH thermostat, additional heat energy is transferred into storage via the two-stage electric
resistance element. Hot water delivery temperatures were tempered by a mixing valve set at 52 ⁰C,
enabling the HPWH tank to act as thermal storage for the PV-generated energy.
Increasing temperatures in a 189-liter tank from the 52 ⁰C baseline upwards to 60⁰C is the thermal
storage equivalent of 1.7 kWh. By adding extra energy past 60 ⁰C into the tank, the system was able
to store an additional 0.5 kWh per day. Therefore, additional thermal storage in the tank from raising
the thermostat setting is equivalent to approximately 2.2 kWh (neglecting standby losses.) Data
indicated that thermal storage levels above 60⁰C appear during 75% of the days analyzed. Peak hot
water temperatures reached past 65⁰C in May and August as measured at the hot water outlet port
during the 3:49 pm hot water draw and average 62⁰C in late afternoons.
On a daily basis, tank heating in response to early morning hot water draws (83 liters) before 7:45 am
was begun typically around 7:30 am, but the heating process was interrupted at 8:30 am by a
thermostat setback to 46⁰C. Hot water recovery using the HPWH compressor is then completed at a
later time in the morning -- 10:30 am when solar resources are typically higher -- by resuming a 52⁰C
thermostat setting. This process is illustrated in Figure 3 showing data recorded on August 23, 2016.
The compressor turns on at 7:38 am for only 10 minutes, due to previous day storage and the 49⁰C
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thermostat setting, and then is followed by 192 Watts of electric resistance heating. The compressor
resumes heating again at 9:07 am due to its thermostat setback of 46⁰C: and completes recovery by
11:30 am. The operation of the two-stage electric resistance heating operation is visible in the
afternoon indicating extra energy being stored at a rate of 396 and 192 Watts, respectively.

Figure 3: Example PV production and HPWH power usage in the prototype PV- HPWH

Results
Figure 4 displays recent results from testing the prototype PV-assisted HPWH in Central Florida. The
bar graph shows the daily coefficient of performance (COP) of the overall system for the month of
September 2016 as defined by the relationship:

Hot water energy out
COP(cid:5)
Grid electrical energy in

Figure 4 also shows the daily solar radiation on the two PV modules (dotted line) in Watt-hours per
square meter per day on the right axis. It is apparent from the figure that COPs above 4.0 are typically
possible on days with daily plane of array solar radiation above 4 kWh per square meter. Variation in
the COP on any particular day is not only affected by the solar irradiance, but also by its distribution
against loads on that particular day. Efficiency is also influenced by the solar irradiance on the
preceding day as this influences the stored thermal energy over evening hours. Overnight tank
thermal storage is particularly important for the efficiency with which early morning hot water draws
are served.

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